A method for forming a trench in a semiconductor substrate includes configuring a mask on the substrate. The mask has a window in which a substrate surface is uncovered. The substrate is electrochemically etched proceeding from the substrate surface. A porous substrate is formed in a trench-shaped region proceeding from the substrate surface. The trench is formed by removing the porous substrate from the trench-shaped region.
Legal claims defining the scope of protection, as filed with the USPTO.
1. A method for forming a deep trench for a trench capacitor in a semiconductor substrate, which comprises: providing a substrate having a substrate surface; providing a mask having a window and configuring the mask on the substrate to define an uncovered portion of the substrate surface that is within the window; electrochemically etching the substrate, proceeding from the uncovered portion of the substrate surface that is within the window, by using an electrolyte containing hydrofluoric acid to form a porous substrate in a trench-shaped region proceeding from the uncovered portion of the substrate surface; oxidizing the porous substrate to form porous substrate oxide; and etching the porous substrate oxide using hydrofluoric acid.
2. The method according to claim 1 , which comprises performing the step of forming the porous substrate such that the porous substrate has a density of between 20% and 80% of that of the substrate.
3. The method according to claim 1 , which comprises including silicon in the substrate.
4. The method according to claim 1 , wherein the porous substrate is converted into the porous oxide using thermal oxidation.
Cooperative Patent Classification codes for this invention. Click any code to explore related patents in that topic.
July 27, 2001
January 6, 2004
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